1. Field of the Invention
The present invention relates to a vehicle seat provided with a height adjuster, and is particularly directed to a structure for such vehicle seat which is adjustable in seating height by operation of the height adjuster.
2. Description of Prior Art
A general structure of conventional seat with a height adjuster is shown in FIGS. 1 and 2 of the accompanying drawings.
The seat comprises a seat cushion (1') and seat back (10). Although not shown, the seat back (10) is rotatably connected via a reclining device with the rear end portion of the seat cushion (1') such that the seat back (10) are adjustably inclined forwardly and backwardly relative to the seat cushion (1') by means of the reclining device.
The seat cushion (1') is basically composed of a frame (11') of a pan type, a cushion member (12') mounted in the frame (11'), and a top cover member (13') which is stretched over both frame (11') and cushion member (12'), excepting the bottom of the frame (11'). The top cover member (13') is formed by a seating surface portion (13a') and side wall portion (13b'), both of which are sewn together at a peripheral corner of the seat (1'). The seating surface portion (13a') is affixed over the corresponding portion of the cushion member (12), defining a seating surface (1a') of the seat (1'), whereas the side wall portion (13b') is affixed over the corresponding portion of the cushion member and anchored at its lower end to the frame (11), thus defining a side wall (1b') of the seat (1').
Under the thus-formed seat cushion (1'), is provided a base bracket (3) which is fixed on the upper rail (91) of a slide rail (9), as shown. The slide rail (9) is adapted for adjusting the fore-and-aft position of the seat cushion (1'), and comprises a lower rail (92) and the upper rail (91), the lower rail (92) being fixed on the floor (F) of vehicle body and the upper rail (91) being slidably fitted in the lower rail (92).
Between the base bracket (3) and seat cushion (1'), is provided a height adjuster referred to as a "height adjusting mechanism" hereinafter and designated generally by (5), which is adapted for adjustably raising or lowering the seat cushion (1'). In brief, referring to FIG. 1, the height adjusting mechanism comprises a connecting rod (51), a link member (52) fixed on the connected rod (51), a bracket (53) fixed on the bottom of the seat frame (1), the lower free end of which bracket is pivotally connected with the free end of the link member (52), a sector gear (54) fixed on the connecting rod (51), a pinion gear (55) in mesh with the sector gear (54), a drive shaft (56) which passes through the base bracket (3) and a side cover (4) in a rotatable matter, the outer end of which drive shaft (56) is provided with an operation handle (57). The pinion gear (55) is fixed on the inner end of the drive shaft (56). The side cover (4) is fixed via a support bracket (41) to the outer planar surface of the base bracket (3) in such a manner as to be disposed laterally and longitudinally of the left-hand lateral side of the seat cushion (1'), base bracket (3) and slide rail (9), as viewed from FIG. 2. For the simplicity sake, description is made only on the left-side portion of the seat cushion (1') and those associated adjusting elements (4, 5 and 9), which are of course provided at the right-side portion of the seat cushion (1') though not shown. Thus, the connecting rod (51) is extended between a pair of spaced-apart base brackets and at both ends rotatably supported by them.
The rotation of the handle (57) causes simultaneous rotation of both drive shaft (56) and pinion gear (55), which in turn causes rotation of both sector gear (54) and connecting rod (51), to thereby rotate the vertical rotation of the link member (52). Accordingly, the seat cushion (1) is raised or lowered in response to such mechanical motions.
Designations (59) denote a reclining-device mounting area formed in the side cover (4) in which an operation part of a reclining device is to be mounted, and designations (57)(58) denote operation handles for operating the height adjusting mechanism, wherein although not shown the former is for adjusting the height of the forward part of the seat cushion (1') and the latter is for adjusting the height of the rearward part thereof. Having a good look at FIGS. 1 and 2, the side cover is formed with two recessed circular portions (4a)(4b) in which are disposed the two operation handles (57)(58) respectively, such that those handles (57)(58) is partly projected externally of the planar side surface of the side cover (4).
Now, the above-described prior-art seat structure is indeed positive in avoiding view of the interior under the seat cushion (1') when the seat cushion (1') is lowered at a lowest level by operation of the height adjusting mechanism (5), at which time, the side wall (1b') of the seat cushion (1') is in contact with the upper edge of the side cover (4), but in contrast, when the seat cushion (1') is raised to a higher level or highest level, as shown in FIG. 1, there comes up a clearance between the side side cover (4) and the bottom of the seat cushion (1'), resulting in the coming into view of the interior under the seat cushion (1') so that some mechanical elements are exposed to view through the clearance (L), impairing the outer aesthetic appearance of the seat and causing an objectionable feeling thereto.